trailer light troubleshooting question

[davemac]

Let me qualify this post by saying that "I know a little bit about a lot of things"....unfortunately electrical troubleshooting is not one of them. I tow behind a Toyota 4Runner w/ (round) 7-pin plug (although I only have a 4 wire system). There seems to be an odd "delay" going on before the trailer lights will operate. If I hook up and test lights in driveway, nothing works. Start driving a short way down the road, and they will come to life. Shut car off, and nothing works again.

Anyone care to enlighten me on this?

Another piece of puzzle I noticed is that if I have AM radio station on and turn lights on w/ trailer attached, it sends awful distortion through radio.

Edited April 26, 2010 by davemac

[Bill_AirJunky]

Do the trailer lights work when hooked up to another truck?

Is your trailer ball clean or rusty?

Your probably going to need to get a test light to check the truck's plug next.

[tuslake]

Let me qualify this post by saying that "I know a little bit about a lot of things"....unfortunately electrical troubleshooting is not one of them. I tow behind a Toyota 4Runner w/ (round) 5-pin plug. There seems to be an odd "delay" going on before the trailer lights will operate. If I hook up and test lights in driveway, nothing works. Start driving a short way down the road, and they will come to life. Shut car off, and nothing works again.

Anyone care to enlighten me on this?

Another piece of puzzle I noticed is that if I have AM radio station on and turn lights on w/ trailer attached, it sends awful distortion through radio.

Its sounds like you have a bad ground,ck auto bat first see if terminals are corroded up,then ck plugs clean them, then use a die elc, grease on them.and give that a shot,good luck!

[REW]

for the AM distortion that sounds like a grounding issue with the radio, for the lights try cleaning the connectors on the trailer and the truck. Get aggressive if you have to they have a tendency to corriod over the winter layup. Also look for loose connections on the trailer the ground plug may have some corrosion on it as well. Shake things around after hooking up without driving jump on the toung and wiggle the connectors on at a time. You should be able to get something to happen without driving.

Good luck these type of problems are hard to find.

REW

[davemac]

thanks, guys. I've got somewhere to start now.

-battery terminals on car are tight and look like new

-sprayed some cleaner on the plugs and put some dielectric grease on them. Both look to be in good shape (truck only a few years old, and the male plug (on the trailer) is new last year.

-trailer ball is clean and new...which leads me to a very stupid question. Is it necessary to be hitched to the trailer for the lights to operate...or is connecting the wiring plug sufficient to test operation?

-Its too dark to check now, but will mess around w/ it some more tomorrow night, and maybe flag down a neighbor to see if lights operate fine hooked up to a different vehicle.

[jk13]

Stupid question answer: no. The one pin in the trailer/truck plug that is opposite the others is the ground (white wire on the trailer usually).

Is this factory wiring on the truck, or aftermarket?

How was the new trailer end attached last season? Please, please don't say wire nuts. However it was done, check those connections as well and make sure the white wire on the trailer is grounded well if it's visible at the front of the trailer.

[davemac]

factory wiring/harness on vehicle. Trailer end was installed by me (no wire nuts), as replacement for flat 4 plug (so I didn't need to use adapter to connect to vehicle's round plug). I siliconed the thing up after install, but will try to open it to confirm all connections still good.

[Bill_AirJunky]

Sounds like you need to test each pin at the plug that you installed.

The system can be hooked up so the ground goes thru the hitch.... or not. Could be either way.

[wakechick3]

I have finicky lights also, I always have to twist the connector at the truck after I have plugged it in..works most of the time.

[davemac]

update...hooked up to neighbor's truck...same problem. Thus, issue lies in the trailer, not vehicle. Checked connections in trailer plug...all look as new. I'm assuming ground (white wire) is bad. Next step (I'm guessing) is to locate where wire is grounded to the trailer. BTW, it is a Performance s/a trailer (non-swing tongue)

Edited April 26, 2010 by davemac

[Ndawg12]

update...hooked up to neighbor's truck...same problem. Thus, issue lies in the trailer, not vehicle. Checked connections in trailer plug...all look as new. I'm assuming ground (white wire) is bad. Next step (I'm guessing) is to locate where wire is grounded to the trailer.

My ground (boatmate trailer) is near where the tongue swings but closer to the boat on the bottom side. Just a black wire with a self-tapping screw.

[davemac]

Problem solved. The ground wire had detached from where it connects to frame. The wire had retracted up into the black plastic "sleeve" (w/ the rest of the wires) so the problem was not readily apparent.

Thanks for the help guys.